PROJECT SUMMARY Neurons in the gustatory portion of the insula cortex (gustatory cortex; GC) integrate information related to the sensory and emotional dimensions associated with the experience of eating. Recent experimental evidence led to the proposal that GC achieves this level of integration by processing sensory afferents from the gustatory thalamus (VPMpc) and limbic afferents from the basolateral amygdala (BLA). However other brain areas may contribute to the integrative properties of GC. One of these areas is the mediodorsal nucleus of the thalamus (MD). MD is a higher order thalamic nucleus often studied in relation to its connection with frontal cortices and for its involvement in processing multisensory and reward-related information. From a neuroanatomical point of view, MD is also well suited to process gustatory information: it receives afferents from the parabrachial nucleus (PBN), a key gustatory nucleus in the brainstem and projects axonal efferents to the insula cortex. Despite this information, no data is available on the potential role of MD in taste. The proposed research relies on multiple experimental approaches to test the general hypothesis that MD provides fundamental reward-related information to GC. Neuroanatomical tracers will characterize the neural pathway connecting MD to GC. Multielectrode recordings in behaving mice will unveil how MD neurons represent the different facets of a gustatory stimuli. Chemogenetics silencing combined with electrophysiology in behaving mice will test the causal role of MD in shaping GC taste processing and taste-related behaviors. Altogether, the experiments outlined in this proposal will lay the foundation for an in depth understanding of the interaction between higher order thalamic nuclei and sensory cortical areas. If successful, the proposed research, will unveil the role of MD in affecting taste processing and its involvement in modulating taste-related behaviors.